This invention relates to sky writing apparatus and methods, and more particularly to a novel sky writing apparatus and method which permits a single airplane to effectively print in the sky letters, words, numbers and designs the printing of which previously required the coordinated efforts of five sky writing airplanes flying in formation.
Sky writing is an art that has been known for many years, and continues to find much popularity in advertising and publicity campaigns. Traditionally, the art comprises two basic forms of writing performed by two different methods, the first and most common method being that a highly skilled flyer in a plane equipped to dispense fog material behind it will literally maneuver his airplane aerobatically to form letters and words in script fashion, the plane essentially acting much like a pencil does on paper.
The second basic form of sky writing, now becoming particularly popular, is sky typing, in which individual, highly recognizable letters form words in the sky. This method involves precision flying by a team of usually five fog emitting planes flying together in formation to form letters and characters of block configuration similar to the characters printed by a typewriter. Each member of the team flies a specific course and direction parallel to one another and emit fog in proper position on a 5.times.5 matrix to form one horizontal part or leg of a letter. His companions, doing their part of the assignment, each forms another horizontal part or leg, and so forth until the letter is completed. Then, the next letter is formed, and on until the word or phrase is completed. Each plane will complete the appropriate legs of successive letters in similar fashion. Therefore a plurality of planes are required to form each letter of each word to be written.
Although sky typing is especially desirable for its highly recognizable lettering, understandably the expense is often prohibitive, as the art requires five specialized planes and highly proficient pilots for each job. Alertness, constant radio contact, pre flight planning and total adherence to individual flight paths are absolute essentials to effectiveness and safety whenever this group of planes work so closely together in such small air space. Special piloting skills are absolutely mandatory, and just as clearly the resulting advertising costs to the customer are correspondingly high.
Another important feature involved in the art of sky writing is the commercial use of fogging agents designed to create streams or puffs of "smoke" in the air. Most often, chemicals are used which react with the moisture in the air to form white oxides, which tend to remain visible for periods of time.
A conventional fogging chemical that is preferred today is titanium tetrachloride, (TiCL4) a liquid which, when atomized and dispersed into the atmosphere, reacts with the moisture in the air and forming a visible titanium oxide. This reaction product is especially white and makes an excellent lettering "smoke".
Traditionally, canisters containing titanium tetrachloride are pressurized with compressed air, which acts as a propellant and carrier to dispense the chemical when a valve is opened. Inherently, as the chemical escapes from the nozzle of the canister when the valve is opened, salts begin to form and very often plug up the nozzle, causing mis-firing, a sticking valve, or failure of the material to dispense further.